Chapter 14: Independent Group t-Test Flashcards Preview

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Flashcards in Chapter 14: Independent Group t-Test Deck (23):
1

When do you go by correlated group design?

- Null- hypothesis population u and o are unknown
- differences between PAIRED scores are analyzed.

2

Experiment with two conditions?

- random sampling of subjects from population.

3

What are the characteristics of Independent groups design?
- ____ of subjects from population
- _____ assignment to each condition
- Each subject is tested how many times?
- What are analyzed?
- t-test analyzes what?

- Random sampling of subjects from population
- Random assignment to each condition
- No basis for pairing of scores
- Each subject is tested ONLY once
- Raw scores are analyzed
- t-test analyzes difference between sample means.

4

What are the alternative hypotheses for Directional and Nondirectional?

- U1 > U2 or U1- U1 does not = U2 (nondirectional)

5

What are the null hypotheses for Directional and Nondirectional?

- U1 <= U2 ( directional )
- U1 = U2 (nondirectional)

6

Sample scores from condition 1 include:?

- U1= mean of pop that receives condition 1
- O1 = standard deviation of the pop that receives condition 1.

7

Sample scores from condition 2 include:?

- U2= mean of pop that receives condition 2
- O2= standard deviation of the pop that receives condition 2

8

What is the major assumption of independent groups design?(3)

- changing level of IV affects MEAN ONLY
- Does not affect standard deviation or variance
Therefore: O^2 1 = O^2 1
- If IV has a real effect the means will differ, not variance
L> IV assumed to equally affect each individual

9

Sampling distribution of the difference between sample means ( X1-X2):
- Draw all possible samples of __ and ___, from a population of __ and __, and standard deviation of __ and __.
- Calculate __ and __ for each sample
- Calculate __-__ for all possible pairings of samples of size __ and __.

- n1, n2, u1, u2, o1, o2
- Xbar 1, Xbar 2
- Xbar 1- Xbar 2
- n1 and n2

10

What is the formula for t-test of independent groups?

- Tobt = (X1-X2) - uX1- uX2/ square root of: S^2w( 1/n1 + 1/n2)

- S^2w = weighted estimate of o^2 (variance)
-

11

What is the computational equation for tobt???

- tobt= (X1-X2)/ square root: (SS1+SS2/n1+n2-2) times by (1/n1+1/n2)

12

What is the formula for df for independent groups?

- N-2

13

Conclusion for independent groups? (t)

- | tobt | >= | tcrit |, reject Ho

14

What is the formula for Tobt when n1=n2 ?
degrees of freedom ?

- Tobt= (X1-X2)/ square root of: SS1+SS2/ n(n-1)
- Df= N-2 (N= population NOT SAMPLE)

15

What is the assumption of independent group t-tests?

- test is robust

16

The sampling distribution is ___ distributed. If __=__ and _>=_.

- normally
- n1=n2
- n>= 30

17

Homogeneity of variance? huh?

- O1^2 = O2^2
L> Mann- Whitney U

18

What is the formula for effect size of independent groups?

- D= | X1- X2| / square root of: S2w
ala --> S2w= SS1+ SS2/ n1+n2-2

19

What increases power??

- Great effect of IV
- Larger sample size
- Decreased variability

20

Correlated t-tests is more powerful when correlation between paired scores is __.

- high

21

What is the equation for confidence intervals?
- 95%
- 99%

- u lower= (X1-X2)- Sx1-x2 t0.025
- u upper= (X1-X2) + Sx1 - X2 t 0.025

- u lower= (X1-X2)- Sx1-X2 t 0.005
- u upper= (X1-X2) + SX1- X2 T 0.005

22

SX1-X2=??

SQUARE ROOT OF: SS1+SS2/n1+n2-2)(1/n+1/n2)

23

When interpreting confidence intervals the probability value applies to the __ not the ___.

- interval
- population mean